Variable inductance



Sept. 11, 1928.

J. C. DE PUE VARIABLE INDUCTANCE Filed ot. 14. 1926 3 Sheets-Sheet Swucmfoz J C De Paar/e J. C. DE PUE VARIABLE INDUCTANCE Sept. 11, 1928.

3 Sheets-Sheet 2 Filed Oct. 14, 1926 avwento'o J- G De Pue f1 Z f z almanac/1 8 Sept. 11, 1928.

J. C. DE PUE VARIABLE INDUCTANCE Filed Oct. 14, 1926 5 Sheets-Sheet vwemfoz Patented Sept. 11, 1928.

UNITED STATES 1,684,013 PATENT OFFICE.

JAMES C. E run, or SAN ANTONIO, 'rExAs, ASSIGNOR or ONE-HALF TO CHARLES A.

MEYER, or sAN ANTONIO, TEXAS.

VARIABLE INDUCTANC'E.

Application filed October 14 1926. Serial No. 141,570.

This invention relates to improvements in variable inductances and seeks, among other objects, to provide an inductance wherein the inductive value of the coil will, in so far as such value may be affected by mechanical change or failure, be practically fixed permanently, and wherein the inherent capacity of the coil will be uniformly distributed throughout the length thereof.

A further object of the inventionjs to provide an inductance so constructed that the inductive values as well as the distributed capacity values of any two of said inductances of like mechanical specifications, will be substantially identical so that said inductances may be embodied in the transformer units of a multi-stage amplifier and varied by a single control with uniform tuning of the coupled circuits.

And the invention seeks, as a still further object, to provide an inductance embodying novel means for obtaining a quick rough variation ofthe inductive value of the coil as well as a deliberate minute adjustment of such value.

Other objects of the invention not specifically mentioned in the foregoing will appear during the course of the following description.

1n the accompanying drawings Figure 1 is an end elevation showing a transformer unit embodying the present invention, a conventional base and panel being shoivn in section.

Figure 2 isa plan view of the unit.

F igure 3 is an enlarged horizontal sectional view particular Ty showing one of the contact members employed at each end of the core of the unit.

Figure 4 is an enlarged sectional view on the line 44 of Figure 2, looking in'the I direction indicated by the arrows.

Figure 5 is a transverse sectional view on the line 55 of Figure 4:, looking in the direction indicated by the arrows.

Figure 6 is an enlarged fragmentary plan view'showing the manner in which the core is threaded to receive the'turns of the coil.

Figure 7 is a fragmentary detail perspective view of the carrier employed.

Figure 8 is a diagrammatic view showing typical circuit connections employed in connection with the unit.

Figure 9 is a plan view showing a plural sheet metal.

ity of transformer units connected for manip-.

ulation by a single control.

Figure 10. is a detail sectional view showing the manner in which the shafts of the 13, the panel being provided, for the purposes of the present invention, with a slot 14. At the angles between the legs 10 and arms 11 are half bearings 15, mating with which are bearing caps 16, and journaled through the bearings thus formed is the shaft l7' of f a rotor. a i

The rotor mentioned includes a cylindrical core 18 of suitable insulating material, and fixed in the ends of the core, as particularly seen in Figure 3, are end members 19 having hubs 20 which are fixed to the shaft 17 so that the shaft and core will thus turn in unison. Wound about the core is a bare coil 21 of wire which, in the present instance, forms the secondary of the transformer unit, and screwed or otherwise secured to the end faces of the hubs 20 are metal contact rings 2 to which the ends of the coil 21 are conn ted. Frcely surrounding the end portions of the shaft. 17' are insulatin collars 23, and'riveted or otherwise secure to said collars are cupped disc-shaped contact brushes-24, the peripheral edges of which are scallopedto .form tongues yieldably bearing against the contact rings 22, the brushes being preferably struck from suitable resilient Fixed in the outer ends of the collars 23 are pins 25 which, as seen in Figure 3, are accommodated in suitable sockets in the bearing members 15 and 16 for locking the collars and consequently locking the brushes against rotation so that the brushes will be held to cooperate with the rings 22. Connected with the brushes are terminals 26 to which the secondary leads are attached.

As shown in detail in Figure 6, the core 18 is formed with a continuous thread 27, between the turns of which is defined a continuous thread groove 28 and, as will be observed, the turns of the coil are wound about the core to lie in said groove, so that said turns arexthus separated and spaced with respect' to each other by the thread. The thread is accurately and precisely formed by a thread cutting machine so that the itch of the thread is thus uniform with resu tant uniformity in the pitch of the thread groove. Consequently, since the turns of the coil 21 lie tightly in said groove, the turns of the coil are accurately and uniformly spaced while the position of eaclf turn relative to the others is identical. Thus, as will be seen, the inherent capacity of the coil is uniformly distributed from end to end thereof while any two inductances of like mechanical specifications will possess identical inductive and capacity values. Surrounding the core 18 near one end thereof, as best seen in Figures 1 and 2, is a primary insulating core 29 which is supported by an arm 30 attached to the leg 10 of one of the angle brackets, and wrapped about said core is a primary coil 31.

Near their outer ends, the arms 11 of the: angle brackets are provided with pairs of alined bearings 32 and 33, and IIlOllIltLd to rock upon said arms is a squared shaft 34 provided at its ends with trunnions 35 journaled in the pair of bearings 32. Fixed to one of said trunnions is a lever 36, and connected to said lever is a spring 37 which is anchored to a pin 38 and tends to turn the shaft in a clockwise direction. J ournaled in the pair of bearings 33 of the arms 11 is a feed screw 39 to one end of which is fixed a sprocket 40, and fixed to the adjacent end of ,the rotor shaft 17 is a like sprocket 41.

Trained about said sprockets is a sprocket chain 42 connecting the shafts to turn in unison. Splined on the screw 39 is a worm gear 43 and, as shown in Figures 4 and 5, the bore of the hub of said gear is preferably flared at its ends so that the gear will slide smoothly over the thread of said screw.

Slidably mounted upon the shaft 34 is a carrier '44 and mating with the carrier is a block 45 connecting the carrier with the shaft, the carrier and said block being notched to accomodate the shaft therebetween. Connecting the block with the carrier is a screw 46 as well as a binding post 47, and screwed on the upper end of said post is a nut 48 for connecting a flexible ground lead to the post. Screwed or otherwise fixed to the inner end of the carrier is a spring contact 49 which receives the binding post 47 therethrough and extends down wardly to yieldably cooperate at its free end with the coil 21 below the horizontal equitorial plane of the core 18. As best seen in Figure 2, the free end of the contact is grooved slightly to fit the wire of the coil and bears against one of the turns only.

At its outer end, thecarrier is slotted longitudinally todefine a pair of spaced paral- .lel side bars 50, and rising from the carrier at the ends of said slot are lugs 51. As seen in Figure 5, the side bars 50 of the carrier are notched at their lower edges to fit the shaft 17 and are provided at said notches with threads 52 normally meshing with the thread of the feed screw 39 while, as will be observed, the worm gear 43 is freely received between said side bars and is of a diameter to project above the level of the upper edges thereof? Journaled through. the lugs 51 of the carrier is a control shaft 53 which extends freely through the slot 14 0f the panel 13, and detachably secured to the outer end of said shaft is an appropriate insulating knob 54. Fixed to the shaft at a point between the lugs 51 is a worm 55 normally meshing with the worm gear 43, and surrounding the shaft atthe ends of the worm are sleeves 56 which abut the lugs for limiting the shaft against endwise movement.

It is now to be noted that since the shaft 34 is constantly under the tension of the spring 37, the carrier 44 will be held, by said spring, firmly against the feed screw 39 while also, the spring contact 49 will be firmly held in engagement with one of the turns of the coil 21. Furthermore, the worm 55 will be held in mesh with the worm gear 43 so that, as will be seen, the knob 54 may be manually manipulated for turning the gear 43 and rotating the feed screw 39. R0- tation of said screw will, through the medium of the sprocket chain 42, effect r'ota tion of the ,core 18 while the threads 52 of the side bars 50 of the carrier will coact with the thread of the screw for feeding the carrier along said screw as the knob 54 is rotated. Accordingly, the spring contact 49 will be advanced to follow the convolutions of the coil 21 as the core 18 is rotated. If desired, the pitch of the thread of the feed screw may be identical with the pitch of the turns of the coil, but if any difference should exist, compensation for such difference maybe made in the ratio of the sprockets 40 and 41. To obtain a quick variation of the effective inductive value of the coil, the knob 54 is gras ed and the carrier tilted upwardly until t 1e worm 55 clears the worm gear 43 and the spring contact 49 clears the coil21, the shaft 34 turning, of course, to accommodate the upward tilting movement of the carrier. Preferably a stop '56 is provided for engagement by the lever 36 to limit the carrier in its upward tilting movement so that in the uppermost position of the carrier, the worm gear 43 will still project between the side bars 50 of the carrier. As soon as the worm 55 clears the worm gear 43, the carrier may then be slid along the shaft 34 to the desired position and, as will be seen, the worm gear 43 will be slid along the feed screw 39 by the carrier so that upon release of the knob 54, the carrier will be returned by the spring 37 into engagement with the feed screw while the worm 55 will be returned into engagement with the worm gear and the spring contact 49 returned into engagement with the coil;

21. Having thus obtained the initial rough adjustment, the knob 54 may be rotated, as previously described, for minutely varying the effective inductive value of the coil.

In Figure 8 of the drawings, I have;

opposite end of said coil with the ground lead 58. The wire 61 also forms a ground lead for the spring contact 49, and connected across the coil 21 is a plurality'of fixed condensers 62 selectively available by means of an appropriate switch 63, the condensers 62 being of different capacity values. Thus, after the switch 63 has been set to connect the desired one of the condensers 62 across the secondar coil 21, depending upon the band in whic any particular wave length is to be found, the effective inductance of the coil 21 may be varied in the manner previously described for tuning the circuit to said wave length.

In Figure 9 of the drawings, I have shown a number of the transformer units connect-ed for operation by a single control, said units being respectively indicated as a whole at 64. A base is indicated at 65, and coupling the rotor shafts of the several units with each other are short coupling shafts 66 connected with the rotor shaft-s by insulating sleeves 67. As shown in Figure 10, one of said sleeves is formed with a sprocket 68. Fixed to the base to project between the units are pairs of posts 69 which journal the coupled ends of the rotor shafts, and likewise fixed to the base are brackets 70 which journal the outer ends of the rotor shafts of the terminal units. The brackets 70 are like the brackets first described, and journaled by the arms of said brackets is a squared shaft 71 as well as a feed screw 72, these parts corresponding to the parts 34 and 39 of the individual unit previously described. The shaft 71 is yieldably held against turning by a spring 73, as in the individual unit, and slidable on said shafts are carriers 74 as well as a master carrier 75. The carriers 74 are like the carrier 44 first describedwith the exception that the carriers 74 are not equipped with control shafts. However, the carrier 75 is identical with the carrier 44 and mounts a control shaft 76 which carries a worm 77 riers 74 and 75 with each other is a tie bar 78, and fixed to the carriers to cooperate with the secondary coils of the several units are spring contacts 79 like the spring contact 49 first described. As will be appreciated, these contacts 79 will be normally held, by the spring tension on the shaft 71, in yielding engagement with said coils. Fixed to the feed screw 72 is a sprocket 80, and trained about said sprocket and the sprocket 68 is a'sprocket chain '81. Thus, as will be seen, when the control shaft 76 is turned, the rotors of the several units will be likewise turned while the carriers 74 and 75 will be shifted laterally by the feed screw 72. By lifting upwardly on the control shaft, the carriers may be rocked out of engagement with the feed screw and the spring contacts 79 swung out of engagement with the secondary coils of the units, when the control shaft 76 may be manipulated for shifting all of the carriers laterally.

Having thus described the invention, what I claim is and rotating the coil in timed relation to each other, said contact being releasable from its feeding means and slidable longitudinally of the coil to effect quick adjustment of the contact.

2. A variable inductance including a rotatable coil, a contact to coact therewith,

means for feeding the contact laterally to follow the turns of the coil, and means for actuating said feeding means and rotating the coil, the contact being slidably shiftable in the direction of the length of the coil when said feeding means and co reat rest.

3. In an inductance, a plum of units including rotatable coils, coupling. said coils to rotate in unison, a feed screw, driving connection between said screw and said coils, carriers, rigid means connecting said carriersand retaining the carriers in permanent spaced relation to each other, one of the carriers being mounted to coact with said feed screw whereby the carriers ma be simultaneously shifted in thedirection o the length of the coil by said screw, spring con- -means for transmitting rotary motion from said shaft to said coil, a rock shaft disposed between-said coil and driven shaft parallel thereto, a carrier slidable upon said rock shaft, a contact extending from said carrier to engage said coil, an actuating shaft rotatably carried by said carrier and by means ly of the coil in timed relation to rotation of the coil.

5. A variable inductance including a rotatable coil, a driven shaft rotatably mounted in spaced parallel relation to said coil, means for transmitting rotary mo,- tion from said shaft to said coil, a rock shaft disposed between said coil and driven shaft parallel thereto, a carrier slidable upon said rock shaft, a contact extending from said carrier to engage said coil, an actuating shaft rotatably carried by said carrier and by means of which the carrier may be tilted and slid longitudinally upon said rock shaft, a worm gear slidable upon said driven shaft and held against rotation thereon, a portion of said carrier straddling said gear and extending across said driven shaft and provided with a threaded face meshing with threads upon the driven shaft, and a worm carried by said actuating shaft and meshing with said gear whereby upon rotating said actuating shaft with the threaded portion of the carrier resting upon the driven shaft rotary motion may be transmitted to the coil and the carrier moved longitudinally of the coil in timed relation to its rotation.

6. A variable inductance including a rotatable coil, a driven shaft rotatably mounted in spaced parallel relation thereto, a rock shaft extending longitudinally between said coil and driven shaft, means for transmitting rotary motion from said driven shaft to said coil, said driven shaft being threaded and formed with a longitudinally extending keyway, a carrier slidable longitudinally upon said rock shaft and having arms extending across said driven shaft and formed with threaded recesses engaging the threads thereof, a contact extending from said carrier and engaging said coil below the horizontal radius there f a worm gear keyed to said driven shaft and disposed between the arms of said carrier, an actuating shaftvrotatably carried by said carrier between it arms andprojecting from the .outer end of the carrier whereby the carrier may be tilted out of engagement with the driven shaft and together with the gear slid longitudinally of the coil and shafts, and, a worm carriedby said actuating shaft and meshing with said gear whereby upon rotating the actuating shaft with the carrier resting upon the driven shaft the coil may be rotated and thecarrier moved longitudinally of the coil in timed relation to rotation of'the coil and said contact follow the convolutions of the coil.

7. A variable inductance comprising bearment by conductors connected with said brackets in insulated relation thereto and disposed about the shaft and having arms bearing against said disks, a driven shaft rotatably carried by said arms, means for transmitting rotary motion from said driven shaft to the shaft of said drum, a carrier slidably and tiltably mounted between said drum and driven shaft and having threaded engagement with the driven shaft, a contact extending from said carrier and bearing against said coil when the carrier is resting upon the driven shaft, an actuating shaft rotatably carried by said carrier and projecting from the same beyond the driven shaft, and means for transmitting rotary motion from the actuating shaft to said drivenshaft whereby when the driven shaft and drum are rotating the carrier may be shifted longitudinally of the drum in timed relation to rotation thereof and the contact retained in proper engagement with said coil.

In testimony whereof I afiix my signature.

JAMES C. DE PU [1 s.] 

